US4651687A - Automatic compression releasing device for four-cycle engine - Google Patents

Automatic compression releasing device for four-cycle engine Download PDF

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Publication number
US4651687A
US4651687A US06/811,785 US81178585A US4651687A US 4651687 A US4651687 A US 4651687A US 81178585 A US81178585 A US 81178585A US 4651687 A US4651687 A US 4651687A
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US
United States
Prior art keywords
moving member
tappet
cam
force
gear
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US06/811,785
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English (en)
Inventor
Masanobu Yamashita
Hiroshi Takada
Takemi Inoue
Suguru Yamauchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kawasaki Motors Ltd
Original Assignee
Kawasaki Jukogyo KK
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kawasaki Jukogyo KK filed Critical Kawasaki Jukogyo KK
Priority to US06/811,785 priority Critical patent/US4651687A/en
Assigned to KAWASAKI JUKOGYO KABUSHIKI KAISHA reassignment KAWASAKI JUKOGYO KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: INOUE, TAKEMI, TAKADA, HIROSHI, YAMASHITA, MASANOBU, YAMAUCHI, SUGURU
Priority to DE3545566A priority patent/DE3545566C1/de
Priority to FR8519305A priority patent/FR2592429B1/fr
Application granted granted Critical
Publication of US4651687A publication Critical patent/US4651687A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L13/08—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for decompression, e.g. during starting; for changing compression ratio
    • F01L13/085—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for decompression, e.g. during starting; for changing compression ratio the valve-gear having an auxiliary cam protruding from the main cam profile
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
    • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
    • F02B2075/027—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle four

Definitions

  • This invention relates to an automatic compression releasing device for reducing the compression pressure of the gas mixture in a combustion chamber by automatically opening the inlet or exhaust valve slightly in starting an engine, thus leading the starting torque of the general-purpose four stroke cycle engine to be minimized for easy start.
  • the automatic compression releasing devices have been developed for practical use, which can lower the compression pressure of gas mixture inside the combustion chamber for a less starting torque by automatically opening the intake or exhaust valve slightly in starting, and to automatically release its function after the engine has come up to a preset speed of rotation.
  • FIG. 7 shows a typical example of the automatic compression releasing devices in accordance with the prior art, relating to the four cycle engine in which the rotation of the cam shaft 1 causes the intake or exhaust valve 5 in the combustion chamber 4 to be opened or closed by reciprocating the tappet 3 through a combination of the cam 2 on the cam shaft 1 and the valve spring 34.
  • the automatic compression releasing device comprises an arcuate moving member 7 rotatably supported by a pin 8 approximately at its center on one half of a side face of the gear 6 integrated with the cam shaft 1 having the cam 2 actuating an either valve as described above; an arm 9 projecting sideways from one end of the inner circumference of the moving member 7 to push up the tappet 3; another arcuate moving member 10 disposed on the other half of the side face of the gear 6; one end of the member 10 rotatably supported by another pin 11 on one end of aforesaid moving member 7; the other end of the moving member 10 provided on its outer circumference with the guide 12 consisting of a plurarity of semi-circle recesses to engage with the separate pin 13 attached on the side face of the gear 6; and a spring 14 extended between one point on said other end of the moving member 10 and the other point on the moving member 7 located on the side opposite to the pin 11 relative to the pin 8.
  • the purpose and object of this invention is to provide an automatic compression releasing device for the four cycle engine, which is simple in construction, dependable in function, easy in assembly and steady in operation, thus eliminating the drawbacks of the prior art.
  • an automatic compression releasing device for reducing the gas pressure in the combustion chamber comprises a single moving member being disposed on a side of the gear integrated with the cam shaft in such a way as to surround the cam shaft; a tappet lifting arm being extended from said moving member to a position where it can push up a tappet in the compression stroke of the engine; two guide slots being bored in either said moving member or the gear, and two pins being planted in the unbored member or gear, so as to engage with said respective slots, where the engagement of said pins with said slots allows said moving member to slide independently along the side of said gear in a predetermined direction; and in the cranking stage, a centrifugal force acting on said moving member in parallel with the rotation speed being designed not to overcome a force acting on said moving member against the centrifugal force, resulting in said moving member is so retained at a position that the face of said tappet lifting arm being kept as projecting outside the base circle of the cam, and the returning force of said moving member acting on said tappet
  • FIG. 1 is a front view of an embodiment for an automatic compression releasing device for the four cycle engine in accordance with the invention
  • FIG. 2 is a sectional view taken along line A--A in FIG. 1;
  • FIG. 3 is a front view of the automatic compression releasing device in FIG. 1 in the normal operating condition
  • FIG. 4 is a front view of another embodiment of an automatic compression releasing device for the four cycle engine in accordance with the invention.
  • FIG. 5 is a front view of the automatic compression releasing device in FIG. 4 in the normal operating condition
  • FIGS. 6a through 6e are illustrations of the operation of the embodiment shown in FIG. 1;
  • FIG. 7 is a front view showing a typical type of the automatic compression releasing device for the four cycle engine in accordance with the prior art.
  • FIGS. 1 and 2 illustrate an embodiment of an automatic compression releasing device for the four cycle engine according to the invention.
  • Numeral 1 is a cam shaft and
  • Numeral 2 is a cam fitted on the cam shaft 1.
  • Numeral 3 is a tappet that opens and closes an intake or exhaust valve 5 in a combustion chamber, which is reciprocated by the cam 2 and a valve spring 34.
  • Numeral 6 is a gear mounted on the cam shaft 1 next to the cam 2, and on the side of said gear 6 a moving member 20 is disposed surrounding about a half of the cam shaft 1.
  • the moving member 20 is slidably supported outwards along the side of the gear 6 by pins 23 and 24 planted in the side of the gear 6 through an elliptical guide slot 21 and an L-shaped guide slot 22 which are respectively bored sideways in the opposite sides in relation to the shaft center line of the cam shaft 1.
  • the moving member 20 has an arm 25 projecting sidewards, in order to lift the tappet 3 at least in the compression stroke.
  • a spring 27 is so extended between the tappet lifting arm 25 and a hole 26 drilled in the side of the gear 6 that said tappet lifting arm 25 is forced to project radially out of the base circle 2a of the cam 2 during the cranking period when the engine is being started.
  • the base circle 2a of the cam 2 is partly removed in order that the cutout can accomodate the protruding tappet lifting arm 25.
  • the moving member 20 is pulled by the spring 27 toward the hole 26, and also is helped by the engagement of the pins 23 and 24 planted in the side of the gear 6 with the guide slots 21 and 22 so that the tappet lifting arm 25 takes such a position out of the base circle of the cam as to effect the compression releasing function.
  • the moving member 20 When cranking the engine at the start, the moving member 20 receives a small centrifugal force corresponding to the rotation speed of the cam shaft 1. But at this time, since the centrifugal force never exceeds the resultant force of the gravity to the moving member, a frictional force between the pin 24 and the guide slot 22, and a tension of the spring 27, the moving member 20 has no relative movement to the gear 6, thus resulting in the tappet lifting arm 25 projecting out of the base circle 2a of the cam 2. Therefore, in the compression stroke, the tappet is raised by the tappet lifting arm 25 while the moving member 20 being supported by the guide slot 22 and the pin 24, resulting in the valve 5 remaining open until near the top dead point of compression stroke to allow the gas mixture to escape, thus minimizing the starting torque.
  • the moving member 20 is so designed as to be forcibly returned in place to regain the compression releasing function by the spring 27 when the engine comes to a halt.
  • the moving member 20 can be returned in place to restore the compression releasing function just before pushing up the tappet 3, through the relative movement of the moving member 20 as shown in FIGS. 6a through 6e, within the last one rotation of the camshaft 1, when the engine is going to a halt, while losing the centrifugal force on the moving member. That's because, in a front view of FIG. 1, the gear 6 rotates anticlockwise, and both the slots 21 and 22 are opened diagonally from top right to bottom left.
  • Arrow G indicates the direction of the force of gravity and Arrow T the direction of the rotation of the cam gear.
  • FIG. 4 shows another embodiment in accordance with the invention in which the like reference numerals are provided for the like parts as those in aforesaid embodiment in FIG. 1, thus a further explanation being eliminated.
  • a moving member 28 with an opening 29 resembling the human heart at the center is located on the side of the gear 6 with the opening 29 being so disposed as to surround the camshaft 1, and, from a narrow protrusion 29a on the opening 29, the tappet lifting arm 25 extends towards the cam 2 to push up the tappet 3 in the compression stroke of the engine.
  • the moving member 28 is supported slidably on the side of the gear 6 in the direction apart from the camshaft 1, by pins 32 and 33 planted on the side of the gear 6 which engage respectively in an L-shaped guide slot 30 and an L-shaped cutout guide slot 31 situated at both opposite ends of the moving member 28 relating to the camshaft 1 on the line perpendicular to that of the up and down movement of the tappet 3.
  • This embodiment is applied to the horizontal type engine having the cam shaft 1 disposed in the direction perpendicular to that of the gravity.
  • the gear 6 revolves anticlockwise viewing from front, when the engine is nearing a halt with a minimum of the centrifugal force, the moving member 28 returns to the position where it can regain the compression releasing function right before pushing the tappet 3 up.
  • the pins are planted on the gear side and the guide slots opened in the moving members, the reverse is also possible, in which the guide slots are opened on the gear side and the pins are planted on the moving member.
  • the automatic compression releasing device for the 4 cycle engines according to the invention requires only a single moving member actuated by the centrifugal force due to the revolution of the cam shaft, and the return spring is not necessarily required in the general vertical type engine, the device can be easily mounted because of its exceedingly simple structure.
  • the automatic compression releasing device can operate in an accurate fashion so as to reduce smooth the start torque and to improve remarkably the operability of the engine in the start.
  • an appropriate determination of the shape of the moving member and a proper design of the center of gravity can eliminate the need for the return spring with the like effect achieved.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve Device For Special Equipments (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
US06/811,785 1985-12-20 1985-12-20 Automatic compression releasing device for four-cycle engine Expired - Lifetime US4651687A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US06/811,785 US4651687A (en) 1985-12-20 1985-12-20 Automatic compression releasing device for four-cycle engine
DE3545566A DE3545566C1 (de) 1985-12-20 1985-12-21 Automatische Kompressionsdruck-Reduktionsvorrichtung fuer einen Vierzylinder-Motor
FR8519305A FR2592429B1 (fr) 1985-12-20 1985-12-27 Dispositif de decompression automatique pour moteur a quatre temps

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US06/811,785 US4651687A (en) 1985-12-20 1985-12-20 Automatic compression releasing device for four-cycle engine

Publications (1)

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US4651687A true US4651687A (en) 1987-03-24

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US06/811,785 Expired - Lifetime US4651687A (en) 1985-12-20 1985-12-20 Automatic compression releasing device for four-cycle engine

Country Status (3)

Country Link
US (1) US4651687A (fr)
DE (1) DE3545566C1 (fr)
FR (1) FR2592429B1 (fr)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4790271A (en) * 1986-05-09 1988-12-13 Honda Giken Kogyo Kabushiki Kaisha Auto-decompression system for engines
US4892068A (en) * 1989-06-09 1990-01-09 Kohler Co. Geared automatic compression release for an internal combustion engine
US4898133A (en) * 1988-12-07 1990-02-06 Kohler Co. Automatic compression release apparatus for an internal combustion engine
US5184586A (en) * 1992-02-10 1993-02-09 Tecumseh Products Company Mechanical compression release for an internal combustion engine
US5197422A (en) * 1992-03-19 1993-03-30 Briggs & Stratton Corporation Compression release mechanism and method for assembling same
US5402759A (en) * 1994-07-08 1995-04-04 Outboard Marine Corporation Cylinder decompression arrangement in cam shaft
US5526784A (en) * 1994-08-04 1996-06-18 Caterpillar Inc. Simultaneous exhaust valve opening braking system
US5540201A (en) * 1994-07-29 1996-07-30 Caterpillar Inc. Engine compression braking apparatus and method
US5647318A (en) * 1994-07-29 1997-07-15 Caterpillar Inc. Engine compression braking apparatus and method
US5823153A (en) * 1997-05-08 1998-10-20 Briggs & Stratton Corporation Compressing release with snap-in components
US5957097A (en) * 1997-08-13 1999-09-28 Harley-Davidson Motor Company Internal combustion engine with automatic compression release
US5957101A (en) * 1997-07-09 1999-09-28 Kohler Co. Automatic compression release mechanism for an internal combustion engine
WO2001059268A1 (fr) 2000-02-08 2001-08-16 Mtd Southwest Inc. Petit moteur a quatre temps a decharge de compression permettant de faciliter le demarrage
US20030172886A1 (en) * 2002-03-14 2003-09-18 Pierik Ronald J. Variable valve actuation mechanism having partial wrap bearings for output cams and frames
US6672269B1 (en) 2002-07-18 2004-01-06 Kohler Co. Automatic compression release mechanism
US6755168B2 (en) 2000-09-23 2004-06-29 Harley Davidson Motor Company Group, Inc. Automatic decompression device for valve-controlled internal-combustion engines
US6978751B2 (en) 2002-07-18 2005-12-27 Kohler Co. Cam follower arm for an internal combustion engine
US20060272607A1 (en) * 2005-06-07 2006-12-07 Grybush Anthony F Mechanical compression and vacuum release mechanism
US20070074694A1 (en) * 2005-06-07 2007-04-05 Tecumseh Products Company Mechanical compression and vacuum release mechanism
CN108087052A (zh) * 2017-12-13 2018-05-29 大连理工大学 一种液压多模式可变气门驱动系统

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4221394C2 (de) * 1992-06-30 2002-07-18 Farymann Diesel Dekompressionsvorrichtung für Brennkraftmaschinen

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3362390A (en) * 1966-02-09 1968-01-09 Wisconsin Motor Corp Automatic compression release
US3381676A (en) * 1967-04-12 1968-05-07 Tecumseh Products Co Compression relief mechanism
US3897768A (en) * 1973-11-19 1975-08-05 Tecumseh Products Co Compression relief mechanism

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5620486A (en) * 1979-07-27 1981-02-26 Matsushita Electric Works Ltd Rotary electric razor
US4610227A (en) * 1984-01-20 1986-09-09 Kubota Limited Automatic decompression system for starting engine

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3362390A (en) * 1966-02-09 1968-01-09 Wisconsin Motor Corp Automatic compression release
US3381676A (en) * 1967-04-12 1968-05-07 Tecumseh Products Co Compression relief mechanism
US3897768A (en) * 1973-11-19 1975-08-05 Tecumseh Products Co Compression relief mechanism

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4790271A (en) * 1986-05-09 1988-12-13 Honda Giken Kogyo Kabushiki Kaisha Auto-decompression system for engines
US4898133A (en) * 1988-12-07 1990-02-06 Kohler Co. Automatic compression release apparatus for an internal combustion engine
US4892068A (en) * 1989-06-09 1990-01-09 Kohler Co. Geared automatic compression release for an internal combustion engine
US5184586A (en) * 1992-02-10 1993-02-09 Tecumseh Products Company Mechanical compression release for an internal combustion engine
US5197422A (en) * 1992-03-19 1993-03-30 Briggs & Stratton Corporation Compression release mechanism and method for assembling same
US5402759A (en) * 1994-07-08 1995-04-04 Outboard Marine Corporation Cylinder decompression arrangement in cam shaft
US5540201A (en) * 1994-07-29 1996-07-30 Caterpillar Inc. Engine compression braking apparatus and method
US5647318A (en) * 1994-07-29 1997-07-15 Caterpillar Inc. Engine compression braking apparatus and method
US5526784A (en) * 1994-08-04 1996-06-18 Caterpillar Inc. Simultaneous exhaust valve opening braking system
US5823153A (en) * 1997-05-08 1998-10-20 Briggs & Stratton Corporation Compressing release with snap-in components
US5957101A (en) * 1997-07-09 1999-09-28 Kohler Co. Automatic compression release mechanism for an internal combustion engine
US5957097A (en) * 1997-08-13 1999-09-28 Harley-Davidson Motor Company Internal combustion engine with automatic compression release
WO2001059268A1 (fr) 2000-02-08 2001-08-16 Mtd Southwest Inc. Petit moteur a quatre temps a decharge de compression permettant de faciliter le demarrage
US6401678B1 (en) 2000-02-08 2002-06-11 Mtd Southwest Small four-cycle engine having compression relief to facilitate cranking
US6659057B2 (en) 2000-02-08 2003-12-09 Mtd Products Inc Small four-cycle engine having compression relief to facilitate cranking
US6755168B2 (en) 2000-09-23 2004-06-29 Harley Davidson Motor Company Group, Inc. Automatic decompression device for valve-controlled internal-combustion engines
US20030172886A1 (en) * 2002-03-14 2003-09-18 Pierik Ronald J. Variable valve actuation mechanism having partial wrap bearings for output cams and frames
US6786185B2 (en) * 2002-03-14 2004-09-07 Delphi Technologies, Inc. Variable valve actuation mechanism having partial wrap bearings for output cams and frames
US6672269B1 (en) 2002-07-18 2004-01-06 Kohler Co. Automatic compression release mechanism
US6978751B2 (en) 2002-07-18 2005-12-27 Kohler Co. Cam follower arm for an internal combustion engine
US20060272607A1 (en) * 2005-06-07 2006-12-07 Grybush Anthony F Mechanical compression and vacuum release mechanism
US7174871B2 (en) 2005-06-07 2007-02-13 Tecumseh Products Company Mechanical compression and vacuum release mechanism
US20070074694A1 (en) * 2005-06-07 2007-04-05 Tecumseh Products Company Mechanical compression and vacuum release mechanism
US7328678B2 (en) 2005-06-07 2008-02-12 Tecumseh Power Company Mechanical compression and vacuum release mechanism
CN108087052A (zh) * 2017-12-13 2018-05-29 大连理工大学 一种液压多模式可变气门驱动系统

Also Published As

Publication number Publication date
DE3545566C1 (de) 1987-09-03
FR2592429B1 (fr) 1989-11-24
FR2592429A1 (fr) 1987-07-03

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